public static void WriteBits(
ImageBinWriter s, ref BitBuffer32 bitBuf, ushort bs0, ushort bs1)
{
Debug.Assert(s != null);
bitBuf.Count += bs1;
bitBuf.Value |= bs0 << (24 - bitBuf.Count);
while (bitBuf.Count >= 8)
{
byte c = (byte)((bitBuf.Value >> 16) & 0xff);
s.WriteByte(c);
if (c == 0xff)
{
s.WriteByte(0);
}
bitBuf.Value <<= 8;
bitBuf.Count -= 8;
}
}
private static void WriteDumpData(ImageBinWriter s, ReadOnlySpan <byte> data)
{
s.WriteByte((byte)((data.Length) & 0xff)); // lengthbyte
s.Write(data);
}
private static void WriteRunData(ImageBinWriter s, int length, byte databyte)
{
s.WriteByte((byte)((length + 128) & 0xff)); // lengthbyte
s.WriteByte(databyte);
}
public static void WriteCore <TImage>(
ImageBinWriter state, TImage image,
bool useFloatPixels, int quality, bool allowSubsample, bool forceSubsample)
where TImage : IPixelRowProvider
{
if (state == null)
{
throw new ArgumentNullException(nameof(state));
}
if (image == null)
{
throw new ArgumentNullException(nameof(image));
}
int width = image.Width;
int height = image.Height;
int comp = image.Components;
if (width == 0 || (height == 0))
{
throw new ArgumentException("Invalid dimensions.", nameof(image));
}
if ((comp < 1) || (comp > 4))
{
throw new ArgumentException("Invalid component count.", nameof(image));
}
image.ThrowIfCancelled();
Span <float> fdtbl_Y = stackalloc float[64];
Span <float> fdtbl_UV = stackalloc float[64];
Span <byte> YTable = stackalloc byte[64];
Span <byte> UVTable = stackalloc byte[64];
quality = quality != 0 ? quality : 90;
quality = quality < 1 ? 1 : quality > 100 ? 100 : quality;
quality = quality < 50 ? 5000 / quality : 200 - quality * 2;
bool subsample = forceSubsample || (allowSubsample && quality <= 90);
ReadOnlySpan <byte> zigZag = ZigZag;
for (int i = 0; i < 64; i++)
{
int yti = (YQT[i] * quality + 50) / 100;
YTable[zigZag[i]] = (byte)(yti < 1 ? 1 : yti > 255 ? 255 : yti);
int uvti = (UVQT[i] * quality + 50) / 100;
UVTable[zigZag[i]] = (byte)(uvti < 1 ? 1 : uvti > 255 ? 255 : uvti);
}
for (int row = 0, k = 0; row < 8; row++)
{
for (int col = 0; col < 8; col++, k++)
{
fdtbl_Y[k] = 1 / (YTable[zigZag[k]] * aasf[row] * aasf[col]);
fdtbl_UV[k] = 1 / (UVTable[zigZag[k]] * aasf[row] * aasf[col]);
}
}
{
Span <byte> head1 = stackalloc byte[24] {
0xFF,
0xC0,
0,
0x11,
8,
(byte)(height >> 8),
(byte)((height) & 0xff),
(byte)(width >> 8),
(byte)((width) & 0xff),
3,
1,
(byte)(subsample ? 0x22 : 0x11),
0,
2,
0x11,
1,
3,
0x11,
1,
0xFF,
0xC4,
0x01,
0xA2,
0
};
state.Write(Head0);
state.Write(YTable);
state.WriteByte(1);
state.Write(UVTable);
state.Write(head1);
state.Write(DefaultDcLuminanceNrcodes[1..DefaultDcChrominanceNrcodes.Length]);